In underwater systems, the combination of atmospheric pressure and water pressure dictates constraints for physical equipment that operates in an underwater environment. For example, self-contained underwater breathing apparatus (SCUBA) gear provides air to a human diver at a pressure that is consistent with the diver's current depth. In such air delivery systems, a first stage regulator compensates for a first level of pressure differential between a high-pressure air source, e.g., a 3000 pound per square inch (PSI) air tank, and a low-pressure hose, while a second stage pressure regulator, e.g., a diver's “in-mouth” or mouthpiece regulator, safely delivers air from the low-pressure hose to the diver's lungs.
The mouthpiece regulator is a “demand” valve configured with a given pressure differential for which a user has to provide a “cracking” pressure (e.g., a small amount of suction) in order to initiate or “demand” a flow of air to the user/diver. These scuba-like systems are not configured for operation with electro-mechanical or mechanical devices that use differential pressures relative to the ambient underwater pressure.